1. Field of the Invention
This invention relates to sterilizing techniques and particularly to a method for killing bacteria in water.
2. Prior Art and Information Disclosure
The nation's water supplies have become chemically and biologically polluted. Ever increasing instances of unsafe and biologically contaminated water are causing public health problems and have brought into sharp focus the ever increasing need for clean safe pathogen free water for human and animal consumption. This need for clean water has led to a number of devices and apparatus for purifying, disinfecting and sterilizing.
Virtually all metropolitan areas in the United States are forced to use some sort of cleaning process to eliminate the suspended solids, pathogens, unpleasant odors and undesirable tastes. Water that is naturally purified and sterilized by the action of aeration, percolation and solar illumination are highly desirable, however, natural filtration through soils and sand is becoming less and less viable as increases in population cause tremendous and significant increases in water usage. More and more we are finding that even rural areas are being forced to deal with dangerously high levels of unwanted contaminants. As a matter of practice, virtually all surface water intended for animal or human contact or consumption must be disinfected, filtered, coagulated or otherwise pretreated for the removal of unwanted and harmful micro organisms (pathogens) such as Psuedomonis Aeruginosa, Giardia, the colifonn group and fecal treptococci.
For reasons of economy and technical simplicity, chlorination is a very common form of pathogenicide. In many cases the amount of chlorine required to achieve the disinfection is so excessive that the resulting odor and taste created by the chlorine itself is objectionable to the consumer. Pathogens are developing immunity to extremely high levels of chlorination and are unaffected by it.
U.S. Pat. No. 3,936,364 to Middle discloses electrolytic introduction of silver ions into water for biocidal puposes. While the addition of silver ions in sufficient concentration required to disinfect water does not adversely affect taste, color or odor of water, the residence times to acheive adequate disinfection may be quite long and therefore not practical. The public health services view a concentration on excess of 0.050 mg/l as grounds for rejection of treatment systems utilizing silver.
A number of apparatus have been disclosed for treating water for removal of metal ions.
U.S. Pat. No. 4,054,503 to Higgins discloses a portable unit including a cathode and anode for removing precious metal from solutions with an arrangement to prevent unauthorized removal of the deposited metal.
U.S. Pat. No. 4,089,768 to Fischer et al discloses a battery operated purification system which operates to purify water only when the voltage applied between electrodes exceeds a battery supply voltage.
Over sufficiently long periods, the anodic units currently embodied in the prior art manifest a major problem, i.e., the electrodes become calcified (calcareous deposits thereon) and biofouled. This biofouling and calcification renders the units ineffective and allow harmful pathogens to go untreated through the unit. In such units, removal of the calcification and biofouling requires disassembly, cleaning and or replacement of the electrodes on a frequent periodic basis.